Ocrelizumab in Breastmilk

Levels of ocrelizumab in breastmilk will be serially evaluated across one drug half-life from women with MS and CIS who are postpartum and lactating at the time of the infusion (whether or not they plan to continue to breastfeed their baby after the infusion). The timeline for breastmilk sample is dependent on infusion schedule and dosing if receiving 600mg infusion x1, collection will occur: before infusion and at 8H, 24H, 7D, 20D, 30D, 60D, and 90D post infusion; if receiving 300mg infusion x2 collection will occur: before infusion 1, at 8H, 24H, 7D, and 14D (before infusion 2) after infusion 1 and after infusion 2 at 8H, 24H, 7D, 20D, 30D, 60D, and 90D in 20. Blood samples to determine serum concentration of ocrelizumab will be collected, when possible, at the 24-hour, 14 day (if receiving 300mg infusion x2), and 20D timepoint(s). Both women continuing to breastfeed their infant post-infusion and those that chose to discontinue will be included in the study. In order to ensure broad collaboration as well as rapid recruitment, samples will be collected from patients fitting eligibility criteria upon referral to our study by other investigators.